Before planting it is a good idea to find your USDA Zone info to figure out your garden schedule. The most important data that the zone info tells us is average last frost and the lowest expected temperature for your area.

The first chance to plant fennel in Lisle can be figured out by using the USDA zone info.

Planting Calendar for Fennel

Frost tolerance for fennel:	Very tolerant of frost.
When to plant:	Up to 7 weeks before last frost.

Since fennel do well in cold you can plant them a lot earlier in the year than other frost tender plants.

The earliest that you can plant fennel in Lisle is February. However, you really should wait until March if you don't want to take any chances.

The last month that you can plant fennel and expect a good harvest is probably September. If you wait any later than that and your fennel may not have a chance to fully mature. If you are starting your fennel indoors then you might be able to get away with starting them a little bit earlier.

Last Frost Date

In Lisle the average date of last frost happens on April 15. You should expect an average low temperature of -15°F in the coldest months of winter.

Since the USDA zone info for Lisle is an average the actual date of last frost will vary from year to year. Half of the time in Lisle you get a frost after April 15 so always be ready to cover your fennel in the event of a late frost.

USDA Zone Info for Lisle

Here is the info for USDA Zone 5b.

Average Date of Last Frost (spring)	April 15
Average Date of First Frost (fall)	October 15
Lowest Expected Low	-15°F
Highest Expected Low	-10°F

This means that on a really cold year, the coldest it will get is -15°F. On most years you should be prepared to experience lows near -10°F.

Plants to Grow in Lisle

You may be interested in your other planting guides for Lisle.